Optical sub-assembly packaging techniques that incorporate optical lenses

ABSTRACT

Techniques for manufacturing an optical transmission device in a manner so that the photonic device is protected from damage that can be caused by exposure to the environment and physical handling are described. The invention involves placing a lens or a lens array over a photonic device, either with or without the use of a receptacle device, such that the photonic device is contained within a sealed cavity. The invention has three main embodiments in which the photonic device can be hermetically sealed, quasi-hermetically sealed, or non-hermetically sealed. The optical transmission device can be configured to serve as an optical receiver, detector, or a transceiver device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.09/568,094, entitled “DEVICE AND METHOD FOR PROVIDING A TRUESEMICONDUCTOR DIE TO EXTERNAL FIBER OPTIC CABLE CONNECTION,” filed onMay 9, 2000, which is now U.S. Pat. No. 6,364,542, to U.S. patentapplication Ser. No. 09/568,558, entitled “ARRAYABLE, SCALABLE ANDSTACKABLE MOLDED PACKAGE CONFIGURATION,” filed on May 9, 2000, to U.S.patent application Ser. No. 09/947,210, entitled “TECHNIQUES FOR JOININGAN OPTOELECTRONIC MODULE To A SEMICONDUCTOR PACKAGE,” filed on Aug. 3,2001, to U.S. patent application Ser. No. 10/006,443, entitled“TECHNIQUES FOR MAINTAINING PARALLELISM BETWEEN OPTICAL AND CHIP SUBASSEMBLIES,” filed on Nov. 19, 2001, to U.S. patent application Ser. No.09/922,358, entitled “MINIATURE SEMICONDUCTOR PACKAGE FOR OPTOELECTRONICDEVICES,” filed on Aug. 3, 2001, to U.S. patent application Ser. No.10/165,553, entitled “OPTICAL SUB-ASSEMBLY FOR OPTO-ELECTRONIC MODULES,”filed Jun. 5, 2002, to U.S. patent application Ser. No. 10/165,711,entitled “CERAMIC OPTICAL SUB-ASSEMBLY FOR OPTO-ELECTRONIC MODULES,”filed on Jun. 6, 2002, to U.S. patent application Ser. No. 09/922,357,entitled “OPTOELECTRONIC PACKAGE WITH DAM STRUCTURE TO PROVIDE FIBERSTANDOFF,” filed on Aug. 3, 2001, to U.S. patent application Ser. No.09/957,936, entitled “TECHNIQUE FOR PROTECTING PHOTONIC DEVICES INOPTOELECTRONIC PACKAGES WITH CLEAR OVERMOLDING,” filed on Sep. 21, 2001,to U.S. patent application Ser. No. 09/922,946, entitled “OPTOELECTRONICPACKAGE WITH CONTROLLED FIBER STANDOFF,” filed on Aug. 3, 2001, thecontent of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to optical transmissiontechnologies, and more specifically to packaging techniques that protectphotonic devices from damage.

BACKGROUND OF THE INVENTION

Optical signal transmission techniques provide the ability to transmitbroad bandwidths of data across large distances. For instance, incomparison to electrical signal transmissions over copper wires, lightis attenuated less in fiber than electrons traveling through copper.Therefore multiple data streams within a single optical transmissionmedium can be transmitted at one time. Also, the light signals travellarge distances before they attenuate to a point in which regenerationof the light signals is required.

Optoelectronic devices, which are a combination of optical andelectrical components, are used to build optical networks. The opticalcomponents generate, receive, and transmit light signals while theelectrical components store and process the signals. Such opticalcomponents include devices such as light emitting and detecting devices,generally referred to as photonic devices, and optical fibers. Exemplaryelectrical components are semiconductor integrated circuit devices.Typically, photonic devices are electrically connected to semiconductordevices and the ends of optical fibers are positioned proximate to theactive areas of the photonic devices. In this way, the photonic devicesemit and detect light signals to and from the optical fibers and thesemiconductor devices drive the photonic devices and receive signalsfrom the photonic devices. Examples of such optoelectronic devices aredescribed in U.S. Pat. No. 6,364,542 issued to Deane et al. and in U.S.patent application Ser. No. 10/165,553, entitled “OPTICAL SUB-ASSEMBLYFOR OPTO-ELECTRONIC MODULES,” both of which are incorporated byreference.

Although various techniques have been developed to effectively connectthe optoelectronic components, improved techniques are still desirablein order to increase the transmission efficiency of optoelectronicdevices and overall reliability. For instance, the optical couplingefficiency between photonic devices and optical fibers commonly requiresimprovement. In one specific aspect, light emitting devices tend to bebiased at high voltage levels, thereby emitting light signals that havehigh intensity levels. These high intensity levels cause the lightsignals to enter the optical fibers with relatively low efficiency.Also, the durability of optoelectronic devices are commonly limited bythe photonic devices, which tend to be delicate devices that areadversely affected by elements such as dust, moisture, printed circuitboard mounting flux residues, cleaning residues, and harsh physicalhandling.

In view of the foregoing, optoelectronic manufacturing techniques toproduce more efficient and reliable devices would be desirable.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to techniques for manufacturing anoptical transmission device in a manner so that the photonic device isprotected from damage that can be caused by exposure to the environmentand physical handling. Such damage can be caused by moisture absorption,dust collection, board mounting flux residues, cleaning residues, wirebonding operations, optical fiber mounting operations, etc. Theinvention involves placing a lens or a lens array over a photonicdevice, either with or without the use of a receptacle device, such thatthe photonic device is contained within a sealed cavity. The inventionhas three main embodiments—a hermetically sealed photonic device, aquasi-hermetically sealed photonic device, and a non-hermetically sealedphotonic device. The optical transmission device can be configured toserve as an optical receiver, detector, or a transceiver device.

One aspect of the invention pertains to an optical transmission devicein which a photonic device is hermetically sealed within a protectivecavity. This optical transmission device includes an impermeable supportblock having a supporting surface and a mounting surface, electricaltraces, at least one photonic device attached to a respective one of thecathode pads and connected to at least one of the anode pads, a metalboundary line formed on the support surface that encircles the photonicdevice, and a glass lens set on top of the metal boundary line such thatit is attached to the support surface of the support block.

Another aspect of the invention pertains to an optical transmissiondevice in which a photonic device is sealed within an quasi-hermeticcavity. This optical transmission device includes an impermeable supportblock having a supporting surface and a mounting surface, two raised andparallel rails formed on the supporting surface and being integrallyformed with the support block, the two parallel rails forming a groovethat runs between each of the rails, an elastic o-ring that is setwithin the groove, electrical traces, a first photonic device, areceptacle that is attached to the supporting surface, the receptaclehaving a protruding rim that conforms to the outline of the parallelrails and which is set within the groove, the receptacle also having afirst receptacle opening, and a first glass lens attached within thefirst receptacle opening.

Yet another aspect of the invention pertains to an optical transmissiondevice in which a photonic device is sealed within a non-hermeticcavity. This optical transmission device includes a support block havinga supporting surface and a mounting surface, electrical traces, a firstphotonic device, and a receptacle that is attached to the supportingsurface, the receptacle securing a first glass lens such that is itpositioned above the first photonic device, the receptacle also having aprotruding rim that is in contact with the supporting surface, thereceptacle having a receptacle cavity that fits over the photonic devicewhereby the photonic device is sealed between the supporting surface andthe receptacle.

These and other features and advantages of the present invention will bepresented in more detail in the following specification of the inventionand the accompanying figures, which illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further advantages thereof, may best beunderstood by reference to the following description taken inconjunction with the accompanying drawings in which:

FIG. 1 illustrates one embodiment of an unassembled optoelectronicsystem designed to protect photonic device 106 within a hermeticallysealed environment.

FIG. 2 illustrates a side, cross-sectional view of optoelectronic systemof FIG. 1.

FIG. 3 illustrates an alternative embodiment of an optoelectronic systemwherein a photonic device is hermetically sealed.

FIG. 4 illustrates a cross-sectional view of an optoelectronic systemaccording to another alternative embodiment of the present invention.

FIG. 5 illustrates a perspective view of a support block and a chipsubassembly, which form an alternative embodiment of an optoelectronicsystem in which a photonic device is to be enclosed within aquasi-hermetic enclosure.

FIG. 6 illustrates a side cross-sectional view of optoelectronic systemin which a support block and a receptacle are shown in an unassembledarrangement.

FIG. 7 illustrates a perspective view of an optoelectronic system thatencloses a photonic device within a non-hermetic enclosure, according toone embodiment of the invention.

FIG. 8 illustrates a side plan, cross-sectional view of theoptoelectronic system shown in FIG. 7.

FIG. 9 illustrates a top plan, cross-sectional view of an optoelectronicsystem that encloses photonic devices within a non-hermetic enclosure,according to an alternative embodiment of the invention.

FIG. 10 illustrates an alternative embodiment of a support block that isdesigned to seal a photonic device within a quasi-hermetic environment.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail with reference toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentinvention. It will be apparent, however, to one skilled in the art, thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known operations have notbeen described in detail so not to unnecessarily obscure the presentinvention.

The present invention pertains to techniques for manufacturing anoptical transmission device in a manner so that the photonic device isprotected from damage resulting from exposure to the environment andphysical handling. Such damage can be caused by moisture absorption,dust collection, board mounting flux residues, cleaning residues, wirebonding operations, optical fiber mounting operations, etc. Theinvention involves placing a lens or a lens array over a photonicdevice, either with or without the use of a receptacle device, such thatthe photonic device is contained within a sealed cavity. The inventionhas three main embodiments—a hermetically sealed photonic device, aquasi-hermetically sealed photonic device, and a non-hermetically sealedphotonic device. The optical transmission device can be configured toserve as an optical receiver, detector, or a transceiver device.

FIG. 1 illustrates one embodiment of an unassembled optoelectronicsystem 100 designed to protect photonic device 106 within a hermeticallysealed environment. Upon assembly, optoelectronic system 100 can be usedto convert optical signals to electronic signals and vice-versa. System100 can be used to build an optical network. Optoelectronic system 100is made up of the following components. First there is the opticalsubassembly 102, which includes a support block 104 and a photonicdevice 106. Photonic device 106 is attached to a front surface 108 ofsupport block 104. Secondly, there is the semiconductor device package(or the chip subassembly) 110, which is a semiconductor integratedcircuit (IC) device that is packaged within a protective body. The ICdevice within package 110 is electrically connected to photonic device106 in order to send and receive signals from photonic device 106. TheIC device and photonic device 106 can be electrically connected byelectrical traces that run along or through the body of support block104.

Thirdly there is a lens 112 that, when assembled, is attached to supportsurface 108 of support block 104 in order to protect photonic device106. Lens 112 is shaped like a cap or an open-ended box. Its open-end isto be placed onto the surface of support block 104 so that lens 112covers photonic device 106 and seals photonic device 106 in ahermetically sealed environment. Then there is a receptacle 114, whichis to be attached to lens 112. Then a ferrule 116, which holds opticalfibers 118 in place, is attached to receptacle 114. After being fullyassembled, optical fibers 118 are in optical communication with photonicdevice 106 and the optical signals that pass through fibers 118 gettranslated into electrical signals within chip subassembly 110, andvice-versa.

FIG. 2 illustrates a side, cross-sectional view of optoelectronic system100 of FIG. 1. FIG. 2 provides an additional view of optoelectronicsystem 100 to facilitate a more thorough understanding of the presentinvention.

The main function of support block 104 is to support photonic device 106so that optical fibers 118 can conveniently be set in opticalcommunication with photonic device 106. To perform this function,support block 104 is formed to have front surface (or supportingsurface) 108 and a bottom surface that is attached to chip subassembly110. In one embodiment, support block 106 is made of an impermeablematerial such as a ceramic. An impermeable material prevents moisture topass through support block 104. By making support block 104 out of animpermeable material, it is possible to hermetically seal photonicdevice 106 within lens 112. In alternative embodiments, support block104 can be formed of permeable materials if it is not important toprotect photonic device 106 from moisture absorption. For instance,support block 104 could be formed of plastic or FR4.

In one embodiment, lens 112 is made of glass because the impermeableproperties of glass is used to ensure a hermetic seal of photonic device106 between support surface 108 and lens 112. Lens 112 can be formed ofmolded high-index glass material. Lens 112 can be either a singlelenslet or an array of lenslets.

In alternative embodiments in which a hermetic sealing of photonicdevice 106 is less important, lens 112 can be made of optical gradeplastics. This is possible when a solder reflow is not required afterthe lens 112 is attached to the ceramic support block 102 or the solderreflow can be carried out at relatively low temperature (lower than 220degrees Celsius).

The cavity within lens 112 is referred to as a lens cavity 126. Lens 112can be placed over photonic device 106 so that photonic device 106 fitswithin lens cavity 126. Rim 124 of lens 112 is rectangular shaped,however, it can have a variety of outline shapes. For example, lens 112could have a rim 124 that has an oval outline shape instead of arectangular shape.

In order to create a hermetic seal between support surface 108 and lens112, a line of metal material 120 is formed around the perimeter ofphotonic device 106. Metal line 120 can be referred to as a metalboundary line 120. A matching line of metal material 122 is formedaround a rim 124 of lens 112. Lens 112 is then attached to supportsurface 108 by placing the lines of metal 120 and 122 together andsolder reflowing them together. Metal boundary line 120 acts as ahermetic sealing joint between lens 112 and support surface 108 suchthat gas and moisture cannot seep between lens 112 and support surface108. Alternative methods of using a metal connecting joint betweensupport surface 108 and lens 122 can also be utilized.

In order to create a hermetic seal around photonic device 106, thematerials used to surround photonic device are impermeable materials. Asdescribed above, each of the lens 112, support block 104, and boundarylines 120 are formed of ceramics, metal, or glass. Materials that arenot used include those that allow for seepage of moisture, such aspolymers and epoxy adhesives. For instance, polymers and epoxy tend toabsorb moisture or outgas and therefore introduce moisture or gas intoan environment.

Interconnecting wires 128 connect anode pads on the surface of photonicdevice 106 to anode contact pads 130 on supporting surface 108. Anodecontact pads 130 are within the limits of metal boundary line 120 sothat they will also be contained within a hermetically sealedenvironment when lens 112 is attached to support surface 108.Interconnecting wires 128 are typically wirebonded onto photonic device106 and anode contact pad 130 in such a way that the wires 128 extendoutwards from photonic device and then bend back towards anode contactpads 130. Lens cavity 126 should have a stand-off height, H_(SO), thatis large enough to allow lens 112 to be placed over photonic device 106without having interconnecting wires 128 touch the inner surface of lens112. Standoff height, H_(SO), is the distance between the inside surfaceof lens 112 and support surface 108 after lens 112 is attached.

By hermetically sealing photonic device 106 between support surface 108and lens 112, photonic device 106 is protected from the elements, suchas dust and moisture. Such elements can adversely affect the operationand reliability of photonic devices. The photonic die, or arrays, willbe completely sealed from the outside and no moisture will be able todiffuse into the photonic cavity. The residual moisture within thecavity will depend on the process used during sealing and on the productreliability requirements. Most hermetic packages currently follow MilSpecs of less than 5000 ppm of moisture content. Such protectionprovides full protection of the photonics during component handling,board assembly, and field operations.

Lens 112 also serves to protect photonic device 106 from physical damagethat can be sustained during handling and use.

Lens 112 can also increase the coupling efficiency between opticalfibers 118 and photonic device 106. With respect to a light transmittingphotonic devices, lens 112 can attenuate the light emitted from photonicdevice so that the emitted light has a smaller intensity upon enteringan optical fiber. This is useful since light transmitting photonicdevices are typically biased at higher than needed voltage levels inorder to operate at sufficiently high data rates. In turn, this causesthe emitted light to have a higher intensity level than it is needed,which causes a safety issue. Therefore, by attenuating the emitted lightwith lens 112, a safe operation can be achieved while required data ratecan be met. On the other hand, with respect to light receiving photonicdevices, lens 112 can magnify or focus light received from opticalfibers so that a higher intensity light signal can be directed intophotonic device 106. This can also increase the coupling efficiencybetween a photonic device and an optical fiber.

When optoelectronic system 100 supports a light detecting photonicdevice, it operates as a receiving device. When optoelectronic system100 supports a light transmitting photonic device, it operates as atransmitter. In some embodiments, optoelectronic system 100 can supportboth a light detector and a light receiver, thereby making system 100 atransceiver. Optoelectronic system 100 can support one or more photonicdevices to create a multi-channel receiver, transmitter, or transceiver.In these embodiments, a single lens 112 can be placed over all of thephotonic devices or one lens can be placed over each photonic device.When multiple lenses are used, multiple metal boundary lines 120 shouldalso be formed on support surface 108 and corresponding metal lines 122should also be formed on the rims of each of lenses 112 in order to forma hermetic seal within each of the lens cavities 126. When a lighttransmitting and a light emitting photonic device is attached to asupport surface 108, two types of lenses can be used. One of the lensescan be a light attenuating lens that is placed over the light emittingphotonic device. Another type of lens can be a light magnifying lensthat is placed over the light receiving photonic device.

Chip subassembly 110, as seen in FIG. 2, includes a semiconductor die200 that is mounted on top of a die attach pad 202 and encapsulatedwithin a protective molding material 204. Up-linking contacts 206 areformed on the top surface of die 200 in order to form an electricalpathway to connect die 200 with photonic device 106. Interconnectingwires 208 connect die 200 to chip contact pads 209, which form thecontact surfaces through which optoelectronic system 100 can beconnected to a printed circuit board or another electronic system. Chipsubassembly 110 in FIG. 2 is referred to as a leadless leadframesemiconductor chip package. However, alternative embodiments of chipsubassembly 110 that have contact surfaces for both making contact withsupport block 104 and an external system can also be used. For instance,standard dual in-line packages, ball grid array packages, and quad-flatpackages can also be used.

Chip subassembly 110 can have various types of contacts for connectionto an electrical system such as a printed circuit board. The contactscan be flush with the side surfaces or extend past the peripheral sidesurfaces. In this way, the CSA can be hotbar reflowed, surface mountreflowed, pluggable. Also the CSA can have a configuration to allow formounting onto an edge or anywhere on a printed circuit board.

Up-linking contacts 206 connected to contact pads 210 on the bottomsurface of support block 104. Electrically conductive adhesive or solder211 can be used to secure this connection. Underfill material 212 isused to fill in the gaps between support block 106 and chip subassembly110 in order to strengthen the connection between the two components.

Receptacle 114 attaches to lens 112 and forms an attachment area forferrule 116. Ferrule 116 is a device that secures one or more opticalfibers 118. As shown in FIG. 1, ferrule 116 secures a ribbon of opticalfibers 118. Receptacle 114 has a receptacle opening 115 that allowslight from optical fibers 118 to travel through lens 112 in order toreach photonic device 106. Receptacle 114 is attached to lens 112 byinserting lens 112 into the receptacle opening 115. Then adhesivematerial 132 is used to secure the connection. Adhesive material can beglue since a hermetic seal between receptacle 114 and lens 112 is notcritical. In the various embodiments of the invention where a lens isattached to a receptacle, the lens can be attached to the receptacle byeither placing the lens within an opening of the receptacle or byattaching the rim of the opening to a front surface of the lens, as willbe described in FIG. 3.

Receptacle 114 has alignment pins 117 that guide ferrule 116 into thecorrect alignment with receptacle 114. Correct alignment between ferule116 and receptacle 117 ensures that optical fibers 118 will correctlyalign with photonic device 106. Receptacle 114 can be made to havevarious sizes and shapes suitable for attaching a ferrule 116 to a lens112.

Manufacturing optoelectronic system 100 involves at least two separatesoldering operations. First, solder is used to attach lens array 112onto support surface 108 of support block 104. Secondly, solder is usedto attach optical subassembly 102 onto chip subassembly 110. Properselection of high-temperature solders is required to follow amanufacturing thermal hierarchy. Exemplary high-temperature solders havehigh lead content (e.g., 10Sn90Pb, or 5Sn95Pb, or 3Sn97Pb) with meltingpoints greater than 300° C. In other words, manufacturing process stepsshould expose the optoelectronic system 100 to a hierarchy of decreasingtemperature exposure so to not adversely affect the integrity ofinterfaces and components assembled in earlier steps. For instance,since lens 112 is attached to support surface 108 before opticalsubassembly 102 is attached to chip subassembly 110, the melting pointof the solder used between lens 112 and support surface 108 should behigher than the solder used between optical subassembly 102 and chipsubassembly 110. High-temperature solder should be used for sealing lens112 to support surface 108. Eutectic solder (63Sn37Pb, meltingpoint=183° C.) can be used to connect optical subassembly 102 and chipsubassembly 110. By following this temperature hierarchy, the solderseal between lens 112 and support surface 108 can remain intact duringthe process of attaching optical subassembly 102 to chip subassembly110.

Epoxy can be used to attach components outside of the lens cavity 126.For instance, epoxy can be used to attach the receptacle to the lens andthe ferrule to the receptacle.

Support block 104 is an low temperature co-fired ceramics (LTCC) modulethat is formed of multiple laminated layers 214 of ceramic material.Metal traces 216 are formed between some of the adjacent ceramic layers214 and conductive vias 218 that pass through the thickness of thelayers 214 connect the metal traces 216. The network of metal traces 216and conductive vias 218 connect the contact pads 210 with the anodecontact pads 130 and a cathode pad 134 on the support surface 108. Thisnetwork of electrical traces 216 and conductive vias 218 is convenientfor maintaining a hermetic seal around photonic device 106 since thetraces 216 and vias 218 are not exposed to the environment and thereforedo not provide a pathway for moisture to seep into the lens cavity 126.

FIG. 3 illustrates an alternative embodiment of an optoelectronic system300 wherein photonic device 308 is hermetically sealed. One differencebetween system 300 and system 100 of FIGS. 1 and 2 is that supportsurface 302 of support block 304 has a recessed surface cavity 306 and aphotonic device 308 sits within surface cavity 306. A second differenceis that lens 310 is substantially flat. Surface cavity 306 is recessedto a depth such that when lens 310 is attached to support surface 302,interconnecting wires 312, which extend from the top surface of photonicdevice 308, do not touch lens 310. The depth of surface cavity 306depends upon the thickness of photonic device 308 and the height ofinterconnecting wire 312. The depth of surface cavity 306 should be setso that interconnecting wires 312 do not touch lens 310. In someembodiments, the surface cavity 306 can extend through multiple ceramiclayers. In some embodiments, lens 310 can have a cap shape as shown inFIGS. 1 and 2.

Anode contact pads 314 are formed on at a level that is higher than thelevel upon which the photonic device 308 is set. This allows shorterinterconnecting wires 312 to connect photonic device 308 and anodecontact pads 314. The height at which anode contact pads 314 can varydepending upon design requirements.

Another difference with optoelectronic system 300 is that photonicdevice 308 is wirebonded to anode contact pads 314 that are locatedabove, as well as below, photonic device 308.

As with system 100 of FIGS. 1 and 2, optoelectronic system 300hermetically seals photonic device 308 between surface cavity 306 andlens 310. Impermeable materials are used to form optoelectroniccomponents immediately surrounding photonic device 308. For instance,support block 304 can be formed of ceramic, lens 310 is formed of glass,and metal boundary lines 316 and 318 are used to attach lens 310 tosupport surface 302 via solder reflow.

Optoelectronic system 300 can also be formed to have multiple surfacecavities 306 that each can contain a photonic device 308. Each photonicdevice 308 can either be an optical transmitter or receiver. Eachsurface cavity 306 is also covered with a respective lens 310. Each lens310 can also be specially manufactured to either magnify or intensify alight signal to increase optical coupling efficiency. In someembodiments, a single lens can have a region that magnifies light whileanother region attenuates light signals. Each lens 310 is attached tosupport block 304 through metal boundary lines 316 to ensure thehermetic seal around surface cavity 306.

FIG. 4 illustrates a cross-sectional view of an optoelectronic system400 according to another alternative embodiment of the presentinvention. In system 400, multiple electrical traces 402 run along thesupporting surface 404 and the bottom surface 406 of support block 408.Electrical traces 402 connect cathode pad 410 and anode contact pads 412to respective contact pads located on bottom surface 406 of supportblock 408 thereby facilitating the electrical connection betweenphotonic device 414 and chip subassembly 416. Electrical traces 402 areshown to be embedded within support surface 404 and bottom surface 406.However, electrical traces 402 can also be formed on top of thesesurfaces. In order to preserve the hermetic seal within which photonicdevice 414 is contained, a layer of glass 415 is formed over electricaltraces 402. In this way, the electrical traces will not create a channelunderneath lens 418 through which air or moisture can seep into lenscavity 420. This can happen if gaps between electrical traces 402 andthe surrounding structure of support surface 404 form. These gaps can beso large that metal boundary lines 422 and 424 cannot sufficiently fillin these gaps to ensure a hermetic seal. Therefore, glass layer 415 isformed over electrical traces 402 and the portion of support surface 404surrounding each of electrical traces 402. As shown in FIG. 4, glasslayer 415 also covers substantially all of support surface 404 andbottom surface 406 except for the areas where conductive contact padsare located. Specifically, no glass layer is formed on support surface404 where cathode pad 410 and anode contact pad 412 are formed, and noglass layer is formed on bottom surface 406 wherever contact pads formaking contact with chip subassembly 416 are formed. In an alternativeembodiment, glass layer 415 can be formed in a more limited area thatincludes only a region where the rim of lens 418 makes contact withsupport surface 404. This glass lens formation would encircle photonicdevice 414, cathode pad 410, and anode contact pads 412.

Glass layer 415 can be applied to support block 408 using varioustechniques such as sputtering. Again, support block 408 is formed of animpermeable material such as a ceramic.

FIG. 5 illustrates a perspective view of a support block 502 and a chipsubassembly 504, which form an alternative embodiment of anoptoelectronic system 500 of the present invention. FIG. 6 illustrates aside cross-sectional view of optoelectronic system 500 in which supportblock 502 and receptacle 508 are shown in an unassembled arrangement.Optoelectronic system 500 is designed to seal photonic device 506 withina quasi-hermetic cavity. The packaging of system 500 is formed bysetting receptacle 508 within a groove 510 that surrounds photonicdevice 506. Receptacle 508 has an opening that secures an optical lens524. Optical lens 524 can be secured to receptacle 508 with adhesivessuch as an epoxy. Receptacle 508 and lens 524 combination forms areceptacle cavity 526 which is placed over photonic device 506 andthereby creates a quasi-hermetic seal over photonic device 506.

A high temperature elastic o-ring 512, which is set within groove 510,helps seal the enclosed area surrounding photonic device 506. O-ring 512is loop of elastic material that conforms to the outline shape of groove510 that encircles photonic device 506. The enclosure around photonicdevice is quasi-hermetic because o-ring is typically made out of heatresistant rubber, silicone, or other polymers, which allows for thetransmission of moisture. The polymers used to form o-ring 512 will,over time, allow some moisture to diffuse in (and out) of the enclosureto reach certain equilibrium. This equilibrium will be governed by theoperating conditions of the module (e.g., power on the photonics, heatdissipated by the photonic device 506, and the external environment).

Another reason why photonic device 506 is sealed within a quasi-hermeticenclosure is because common adhesives, such as epoxy, are used to securelens 524 within receptacle 508. As mentioned above, most of suchadhesives tend to outgas and therefore introduce gases into theenclosure. Low outgassing polymer materials are now commerciallyavailable and the materials that cure without outgassing are beingdeveloped.

Groove 510 is created with the parallel set of rails 516 that run aroundthe perimeter of photonic device 506. Rails 516 are integrally formedfrom the material of the supporting surface 518 of support block 502.Receptacle 508 has a protruding receptacle rim 520 that is designed tofit into groove 510. O-ring 512 will correspondingly be compressed whenrim 520 is set into groove 510. O-ring 512 serves to seal the enclosedarea between receptacle 508 and support surface 518. The height, width,and separation of rails 516 can be adjusted depending upon the size ofthe o-ring and the size of receptacle rim 520 that is to be insertedinto groove 510.

Standoff stems 522 also extend from receptacle 508. Standoff stems 522make contact with support surface 508 and maintain a certain distancebetween receptacle 508 and support surface 518. Specifically, supportstems 522 maintain a separation distance between conductiveinterconnecting wires 528 and lens 524. Interconnecting wires 528 tendto be fragile and are easily broken. Therefore, standoff stems 522 serveto protect interconnecting wires 528 and the connection of photonicdevice 506 to the electrical traces within support block 502. Standoffstems 522 can be multiple individual stems or a continuous rim thatextends around rim 520. The shape and size of standoff stems 522 canvary so long as stems 522 serve to maintain the required separationdistance between lens 524 and support surface 518.

Standoff stems 522 are located outside of the receptacle rim 520 andtherefore make contact with support surface 518 outside of thequasi-hermetically sealed receptacle cavity 526. Standoff stems areattached to support surface 518 using adhesive material 530. In analternative embodiment, standoff stems 522 are located within theboundary created by receptacle rim 520.

Receptacle 508 can be formed of various materials such as plastic.Support block 502 need not be formed of impermeable material since thesystem 500 is a quasi-hermetic packaging configuration. However, in someembodiments, support block 502 can be formed of a ceramic material.

In an alternative embodiment, optoelectronic system 500 can bemanufactured so that more than one receptacle can be attached to supportsurface 518. In this embodiment, support surface 518 can have multiplesets of parallel rails 516 and associated grooves 510. In this case,support surface would likely support multiple photonic devices 506, eachbeing covered by a respective receptacle and lens combination.

In another embodiment, one receptacle has multiple openings with eachopening supporting an optical lens. Each optical lens is supported overa photonic device and can be tailored to either intensify or attenuatelight signals. In all embodiments of optoelectronic system 500, eitherlight emitting or receiving devices can be attached to support surface518 to create an optical transmitter, receiver, or transceiver.

FIG. 10 illustrates an alternative embodiment of a support block 1000that is designed to seal a photonic device 1002 within a quasi-hermeticenvironment. Support block 1000 is different in that groove 1004 is setinto the surface of block 1000. Groove 1004 encircles photonic device1002 such that it has a circular or ovular outline shape on thesupporting surface of support block 1000. Forming the inset groove 1004allows protruding rails, as shown in FIGS. 5 and 6, to be optional.Actually, FIG. 10 does not utilize any protruding rails to form groove1004. O-ring 1006 is set within groove 1004 and will be squashed whenrim 1008 is inserted into groove 1004. The squashed o-ring 1006 acts toseal the connection between groove 1004 and rim 1008. In the embodimentof FIG. 10, rim 1008 is taller than rim 520 of FIGS. 5 and 6 since rim1008 must extend into the inset groove 1004. Rim 1008 will also betaller than support stems 1010 since support stems 1010 make contactwith the surface of support block 1000.

FIG. 7 illustrates a perspective view of an optoelectronic system 700that encloses a photonic device 702 within a non-hermetic enclosure,according to one embodiment of the invention. FIG. 8 illustrates a sideplan, cross-sectional view of optoelectronic system 700 shown in FIG. 7.Photonic device 702 is enclosed within a receptacle cavity 704 that iscreated with receptacle 706 and lens 708. Receptacle 706 has an openingthat secures lens 708 so that lens 708 will be secured over photonicdevice 702. Lens 708 is secured to receptacle 706 with adhesive material709, such as epoxy. Receptacle 708 also has a receptacle rim 710 thatencircles lens 708. Receptacle rim 710 defines part of receptacle cavity704 and is attached to support surface 712 of support block 714 withadhesive material 716. The use of adhesive material to attach lens 708to receptacle 706 and receptacle 706 to support surface 712 allows thepossibility of the adhesive materials to outgas into receptacle cavity704. Because of this, receptacle cavity 704 is not completelyhermetically sealed. In one embodiment, a low shrinkage, low moistureabsorption and low out-gassing epoxy material is used as the adhesiveagent.

Photonic device 702 is protected from physical damage since receptaclerim 710 is a solid rim that completely encircles lens 708. Thisconfiguration allows photonic device 702 to be completely sealed withinreceptacle 706 and lens 708. In an alternative embodiment, receptaclerim 710 can be composed of individual stems that do not enclose photonicdevice 702 within a completely enclosed receptacle cavity 704.

FIG. 9 illustrates a top plan, cross-sectional view of an optoelectronicsystem 900 that encloses photonic devices 902 and 904 within anon-hermetic enclosure, according to an alternative embodiment of theinvention. System 900 includes a receptacle 906 that has two openingsthat each secure a respective optical lens 908 and 910. Lenses 908 and910 are secured within the openings with an adhesive agent such asepoxy. Lenses 908 and 910 can be designed to either intensify orattenuate light signals depending upon the type of photonic device thatthey cover. Again, photonic devices 902 and 904 can both be opticaltransmitters, optical receivers, or one of each.

Receptacle 906 is attached to supporting surface 912 of support block914 at points surrounding each of photonic devices 902 and 904.Receptacle 906 is attached to support surface 912 with receptacle rim916, which completely surrounds photonic devices 902 and 904. Receptaclebar 918 extends between photonic devices 902 and 904 provides foradditional attachment regions between receptacle 906 and support surface912. Receptacle bar 918 is a solid structure that completely separatesphotonic devices 902 and 904. Receptacle rim 916 and bar 918 completelyenclose photonic devices within respective enclosures and therebyprotect photonic devices 902 and 904 from structural damage. Receptaclerim 916 and receptacle bar 918 are attached to support surface 912 withadhesive material 920.

In alternative embodiments, receptacle rim 916 and bar 918 can besubstituted with multiple standoff stems that are separate from eachother.

While this invention has been described in terms of several preferredembodiments, there are alteration, permutations, and equivalents, whichfall within the scope of this invention. It should also be noted thatthere are many alternative ways of implementing the methods andapparatuses of the present invention. It is therefore intended that thefollowing appended claims be interpreted as including all suchalterations, permutations, and equivalents as fall within the truespirit and scope of the present invention.

1. An optical transmission device comprising: an impermeable supportblock having a supporting surface and a mounting surface, the supportingsurface having at least one cathode pad and a plurality of anode pads,and the mounting surface having a plurality of contact pads; electricaltraces that connect the cathode pad and the anode pads to the contactpads; at least one photonic device attached to the cathode pad andconnected to at least one of the anode pads; a metal boundary lineformed on the support surface that encircles the photonic device; and aglass lens set on top of the metal boundary line such that it isattached to the support surface of the support block, the glass lensconfigured to hermetically seal the photonic device between the supportsurface and the glass lens whereby the photonic device is protected fromenvironmental and structural damage.
 2. An optical transmission devicerecited in claim 1 wherein the glass lens further comprises: an outerrim having a shape that conforms to and is attached to the metalboundary line, and a lens cavity that fits over the photonic device. 3.An optical transmission device recited in claim 2 further comprising: atleast one interconnecting wire that extends outwardly from a top surfaceof the photonic device and then bends back to make contact with one ofthe anode pads, whereby the interconnecting wire serves to connect thephotonic device to the one anode pad; and wherein the lens cavity has astand-off depth that is sufficiently large so that the interconnectingwire fits within the lens cavity without touching the glass lens.
 4. Anoptical transmission device recited in claim 2 wherein the glass lenshas a cap shape.
 5. An optical transmission device recited in claim 1wherein the support block is formed of ceramic.
 6. An opticaltransmission device recited in claim 5 wherein the support block isformed of multiple laminated layers of ceramic material, and wherein theelectrical traces are formed by a plurality of conductive pathways thatare sandwiched between adjacent ceramic layers and conductive vias thatpass through the thickness of each of the ceramic layers in order toconnect the conductive pathways.
 7. An optical transmission devicerecited in claim 1 further comprising: a packaged semiconductor devicepackage that includes a semiconductor die that is packaged within aprotective molding material, a first set of electrical contact surfacesthat are attached to the contact pads on the mounting surface of thesupport block, and a second set of contact surfaces capable of beingconnected to an external system.
 8. An optical transmission devicerecited in claim 1 further comprising: a receptacle that is attached tothe glass lens, the receptacle having an opening through which the glasslens is exposed such that an optical pathway from the photonic device,through the glass lens and through the opening in the receptacle isprovided.
 9. An optical transmission device recited in claim 1 whereinthe metal boundary line also encircles the cathode pad and the anodepads.